Cladonia lichen found at Longshaw in March on wood.
Using the following features I named this as likely Cladonia macilenta using Frank Dobson’s book.
Colour: grey
Sorediate: yes
Podetia texture: lower squamulose, uppper sorediate, with bare patches
Podetia branching: not significant – some slight branching at apex
Cups: none
Basal squamules: small, densely matted, “frilled”, sorediate below.
Apothecia/pycnidia: small, red, frequent
Split in podetia: not present
K+ (yellow cortex, red apothecia/pycnidia)
Keys out to Cladonia macilenta mainly based on matchstick-like podetia, grey colour and small red apothecia/pycnidia. However, Cladonia seems to be a genus which is variously interpreted, and there are also the difficulties of stunted growth (due to poor air quality), mixed-up colonies of different species, and variability in colour depending on habitat (shady/bright). Apparently the genus is currently under revision.
Steve